Vocal learning by songbirds provides a model for studying general mechanisms of sensorimotor[unreadable] learning with particular relevance to human speech learning. For both songbirds and humans,[unreadable] hearing the sounds of others, and auditory feedback of oneself, plays a central role in vocal[unreadable] learning. Our previous work suggests that a basal ganglia-forebrain pathway participates in[unreadable] processing auditory feedback and in driving experience-dependent changes to vocalizations.[unreadable] Moreover, these experiments suggest that variability introduced from basal ganglia circuitry to song[unreadable] motor structures and behavior may play a crucial role in enabling song plasticity. Here, we propose[unreadable] to further test this idea by combining behavioral and neural approaches to study contributions of[unreadable] variability to song production and plasticity. We will use chronic recordings from basal ganglia[unreadable] circuitry and song motor structures in singing birds to characterize normal levels of behavioral and[unreadable] neural variation as well as to examine neuron-neuron and neuron-behavior co-variation (Aim 1).[unreadable] We will then use feedback manipulations in adult birds to drive adaptive changes in song and study[unreadable] the relationship between behavioral variability and the capacity for plasticity (Aim 2). Finally, we will[unreadable] monitor and manipulate activity (via chronic recordings and lesions) during conditions of adaptive[unreadable] plasticity to investigate mechanisms underlying the generation of neural variability and their[unreadable] requirement for behavioral change (Aim 3). Songbirds provide a system where the influence of[unreadable] performance-based feedback on a well-defined and quantifiable behavior potentially can be[unreadable] understood at a mechanistic level. Such an understanding will provide basic insight into normal[unreadable] learning processes and contribute to our ability to prevent and correct disabilities that arise from[unreadable] dysfunction of these processes.